When block 494,784 is mined (on or around November 16th), the second and final part of an important network upgrade to the Bitcoin protocol called "SegWit2x” will take place. Below is a quick breakdown of what to expect throughout the coming weeks.
Some background on SegWit2x
SegWit2x is essentially a software upgrade that will bring improved capacity to the Bitcoin protocol. A majority of Bitcoin miners have signaled their intent to deploy Segwit2x, which increases the base size of bitcoin transaction "blocks" (groups of bitcoin transactions). The final part of this change is scheduled to occur when bitcoin block 494,784 is mined. Right now, this protocol change will likely activate on or about November 16th.
How does Blockchain plan to respond to SegWit2x?
Our team is working around the clock to ensure our platform is prepared to incorporate these changes to the network as quickly as possible. During the upgrade period, we will take steps to ensure users are protected and their funds are safe.
To keep your funds safe while the network is in transition, we will temporarily suspend bitcoin send, request, and exchange functionality roughly 24 hours before the time of the fork until the network stabilizes. Additionally, we will be suspending all buy and sell functionality roughly four days before the fork.
What happens if there is a network split?
There is a significant possibility that the planned hard fork will result in two bitcoin block chains. In this case, we will follow the chain with the most accumulated difficulty and refer to that chain as bitcoin. If the minority chain has significant value, we will make that value available for customers to hold or exchange for a period of time, as we have done with Bitcoin Cash. If the minority chain is the one with 1MB blocks, we plan to call it BC1. If the minority chain has 2MB blocks, we plan to call it BC2.
Is there any action I need to take in advance?
While no immediate action is required, we encourage you to write down your backup phrase if you haven’t already.
Will I be able to see my bitcoin in my Blockchain wallet?
Yes. We will temporarily be suspending transactions for bitcoin, but your funds will remain safe and you’ll be able to monitor them from within your Blockchain wallet. Please note, until the network stabilizes, your bitcoin’s fiat balance will be based on the value of bitcoin at the time of the hard fork.
Can I use ether during SegWit2x?
Yes, ether will be available during SegWit2x. If you have transactions you need to make during this time, we recommend using ether to send and request.
When are you suspending buy and sell functionality for bitcoin?
We will be suspending all buy and sell functionality roughly four days before the fork.
Where can I find the latest updates?
We’ve created a status page where we’ll be posting regular updates throughout. We will have updates featured on throughout the wallet as well
REFERENCE
https://blog.blockchain.com/2017/11/03/segwit2x-frequently-asked-questions/